The overall objective of this research program is to contribute to the understanding of eye movement initiation and integration. We will examine the electrophysiological responses of cells in an extraocular muscle (EOM) nucleus as well as the motor unit mechanical characteristics of the corresponding EOM. We specifically plan to study the motoneurons and interneurons of the cat abducens nucleus through the use of: 1) intracellular recordings of the cell responses to some of their known inputs (superior colliculus and oculomotor nucleus); 2) intracellular stimulation of the motoneurons while recording motor unit tension, in order to evaluate single motor unit mechanical characteristics at the lateral rectus and retractor bulbi muscles; 3) stereotaxic indices in the mapping of any neuroanatomical organization of abducens nucleus cells in relation to their inputs and motor unit characteristics; and 4) intracellular injection of horseradish peroxidase (HRP) into some physiologically identified neurons in order to better determine their location within the abducens nucleus and to ascertain their morphological features. The research plan, therefore, is to compare and contrast both the motoneuron and interneuron populations with regard to some of their known inputs, outputs and anatomical features. We will, thereby, extend our basic understanding of the functional and anatomical organization of abducens nucleus neurons and their roles in some aspects of eye movement control.